Mitt Romney finally scored that knockout blow he had been looking for throughout the primaries. According ton one report, it is “highly likely” that Gingrich will endorse Romney as he suspends his campaign.

So what now? Well, Romney will obviously be the nominee. That was a strong likelihood before Rick Santorum dropped out and became certain once Santorum suspended his campaign. But Santorum’s exit gave Gingrich an opportunity to become a protest vote for those who were unhappy about Romney’s nomination, which even yesterday’s primaries ranged from about a third of Republicans turning out in the Romney-friendly New England states to more than 40 percent in Pennsylvania and Delaware. That would have made Gingrich somewhat relevant to the race again even though he was too far behind to actually win, and would allow him to close his campaign on somewhat of an up note.

Last night’s results made clear that this wasn’t likely to happen. Now deeply in debt, Gingrich doesn’t really have the resources to fight on in North Carolina and Texas. It’s not clear he will even finish second in other remaining primaries, after running third or worse everywhere but Delaware last night. Gingrich always ran an underfunded and undiscipline campaign, which he was able to keep alive by excelling at free media opportunities like debates and collecting super PAC money from Sheldon Addelson. Both sources of oxygen have since been cut off.

Now Ron Paul, whose campaign still has money, will keep trying to dominate the delegate selection process in enough caucus states to get his name placed in nomination in Tampa while seeking Virginia-like primary results in a few remaining large states. In Virgina, Paul was the only candidate on the ballot with Romney and he managed to break 40 percent. But last night’s results showed consolidating the anti-Romney vote isn’t easy, and that vote may shrink with Gingrich’s departure. The reality of a Romney nomination is setting in.